# Table A: Dimensions of Redesigned Vehicle

2

3

### Display the Data

1. Display data from prototype vehicle.

Table A: Dimensions of Prototype

Mass (g) Length (cm)

Table B: Speed of Prototype

Trial

1

Distance (cm)

100

Time (s)

100

100

Average

Speed (cm/s)

2

3

2. Display data from redesigned vehicle.

Table A: Dimensions of Redesigned Vehicle

Mass (g) Length (cm)

Table B: Speed of Redesigned Vehicle

Trial

1

Distance (cm)

100

Time (s)

100

100

Average

Speed (cm/s)

### Identify the Question to Investigate

Question: In what ways can the prototype mousetrap car be modified to travel at a faster speed using the materials provided?

### Thinking About Mouse Trap Cars

Newton’s First Law of Motion (Law of inertia):

An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Newton’s Second Law of Motion:

Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

Newton’s Third Law of Motion: For every action there is an equal and opposite reaction.

Think About: How is force (mass × acceleration) generated to overcome the inertia of your car? Will a lighter and smaller car require less energy and force to start moving?

What if your car is too light?

Friction is a force that operates in an opposite direction to movement. Traction is friction that is used to advantage.

Think About: Can traction be improved with changes to where the string wraps around the axle? Where the wheels contact the floor? Where else might traction be improved?

What about fluid friction (air resistance)? Will changing the shape of your car make it easier for air to be pushed aside?

Potential Energy is the energy that is in a stored state and has the potential to do work.

Kinetic Energy is the energy that a moving object has.

Think About: In a mousetrap car designed for distance, energy needs to be expended at what rate? In a mousetrap car designed for speed, energy needs to be expended at what rate?

Wheel-to-Axle Ratio: The larger the size of the circumference of a wheel, the greater the distance covered in one axle rotation.

Think about: Will heavy smaller wheels be offset by larger, lighter wheels when designing a car for greater speed?

Torque is the force that causes a wheel to rotate around an axle.

Think about: Changing the length of the lever arm on the mousetrap will not change the torque, but it may change the amount of pulling force. Will a shorter arm or longer arm maximize acceleration? Will energy be wasted by an arm that is too short?

### STEM CUP Constraints:

The vehicle must be powered by one or more mouse traps of the type provided in the materials.

The vehicle cannot have any additional potential or kinetic energy at the start other than what can be stored in the mouse trap's spring itself. (This also means that you cannot push start your vehicle.)

The vehicle must pass the inspection: o fit entirely within the box (length & width of vehicle) o mass between 120 grams and 180 grams o teams must present and explain their modifications to the protocol design at this time

Time of run will begin when any part of the vehicle passes over the start line and will end when that same point passes over the 3-meter mark (finish line).

Materials, distance, car specifications, racing surface, and other constraints will be decided by r acing’s governing body and can be changed at any time.

### Draft a Plan for the Investigation

Describe revisions to the prototype. Include ideas, notes, observations and sketches.

### Test and Revise the Plan

1. Test the new design and record data in the table on page 8.

2. Revise and test again as necessary and update sketches.

### Analyze the Data and Draw Conclusions

What worked? What did not work?

2. What questions do you have now? Identify questions you have now about modifying mousetrap cars for greater speed.

### Assess the project

The project will be assessed with a race.

Nationwide Series: Each team will compete against another team or teams. The best in each heat will advance to the Sprint Cup.

Sprint Cub Series: Winner is named the STEM Challenge

Champion.